As competition in the field of electric appliances has become increasingly fierce over recent years, more demanding technical requirements are being posed on products. For example, products are now required to be energy saving and environmentally friendly, and have a high degree of controllable intelligence, a short development period, and low noise. Electric motors, as the core part, have undoubtedly become a key part to solving the above-mentioned technical problems. Motors in conventional household central air conditioners are typically single phase permanent-split capacitor AC motors (PSC). However, single phase AC motors have low efficiency, consume more energy, have high noise, and have a low degree of controllable intelligence.
As a result of advances in motor technologies, permanent magnet (PM) synchronous motors have been developed. PM synchronous motors typically have a motor controller to electronically commutate current. As a result, PM synchronous motors are also referred to as electronically commutated (ECM) motors. PM synchronous motors are characterized in that they are energy saving and environmentally friendly, they have relatively high reliability and controllability, generate low noise, are easily made more intelligent, and can address the drawbacks of single phase AC motors. Therefore, the single phase AC motors in conventional household central air conditioners are gradually being replaced by PM synchronous motors. However, circuit ports are quite different for single phase AC motors and PM synchronous motors, which creates a problem because it is difficult for one motor to have two different circuit ports. When a conventional PM synchronous motor is used to replace the single phase AC motor in an existing household central air conditioner, it is necessary to replace the circuit port of the motor, change the motor circuit, etc., making the replacement inconvenient and costly.
In view of the foregoing drawbacks, ECM motors have been developed to directly replace the original PSC motors without the need to change the circuit structure of the original application systems of the PSC motors, e.g., the HVAC control system. The installation and troubleshooting of ECM motors in HVAC systems is simple, and the development cost associated with an ECM motor is lower than that of a PSC motor.
However, current ECM motors used to replace single phase AC motors still have numerous problems, a few of which are listed next.
1) The ECM motors have a single function and cannot be used for different applications. For example, they cannot be used to replace ECM motors currently on the market to detect AC input tap signals. As a specific example, an X13 motor has tap input signals at 24 VAC, while tap input signals for the current ECM motors that replace the PSC motors are 115 VAC or 230 VAC, therefore the two are not compatible. In addition, operational parameters for power source voltage, turning, and reprogramming cannot be directly configured for the current ECM motors that replace the PSC motors, and it is relatively inconvenient to configure the settings. As a result, more models must be developed, disorganized products are made, and management and costs are increased.
2) Low reliability; because different applications have different requirements for the ECM motors, it is easy for errors or accidents to take place when the ECM control is unable to adapt to different applications.
3) In conventional systems, a current transformer and relevant circuits are used to detect the state of all tap input lines. However, because the transformer has a large volume and high cost, the transformer takes up a large space of the motor controller, which causes the motor controller to have poor heat dissipation.
4) A plurality of current transformer sensing units are embedded into the wiring plug of the motor, which makes installation difficult, production efficiency low, and large scale production difficult. The aforementioned drawbacks of current ECM motors are not intended to be an all-inclusive list, as numerous other drawbacks exist.